Do plants make the world heavier?

Through photosynthesis, do plants take light energy from the Sun, convert it into mass and actually add to the overall mass of the Earth?

The person who asked this question is probably referring to Einstein’s famous equation E=mc2. However, plants are no particle physicists and cannot convert energy into mass. What they can do better than any human chemist though, is to capture the energy contained in sunlight and use this to combine two of the most abundant compounds on earth, carbon dioxide and water, into glucose.

Glucose, or grape sugar as it is also known, is used by living creatures ranging from yeast to elephants as a carrier of readily available energy. The only ones that can actually make it from scratch (or rather CO2 and H2O) are plants, however.

To do this, they need energy and a catalyst, because these two compounds don’t spontaneously combine to form glucose, as everyone who has ever drunk a glass of sparkling water knows. The two partners need to be coaxed together, and get ‘excited enough’ before they will form a more permanent bond. The matchmaker in this case is called chlorophyl.

Chlorophyl is the substance that gives all leaves their green colour. It is a protein which is able to capture the energy contained in sunlight, and use this to ‘excite’ CO2 and H2O to such a level that they are willing to combine into a new substance called glucose. The actual equasion describing this chemical reaction is depicted on our homepage.

The important thing to note here is that glucose becomes a ‘carrier’ of the energy that was used in its creation. When you run up the stairs and ‘burn’ glucose in your muscles by combining it with oxygen, this is just a way to release this energy to power your muscle cells, and the glucose is reverted back to the CO2 and H2O it was made out of by a crafty plant. When you stand panting on top of the stairs, you are releasing them back into the world, where they will be ready for absorption by another plant to start the whole cycle again.

So, in conclusion, no mass is being created by plants, they just temporarily capture energy into mass.

The conclusion statement seems to be self contradictory:
“So, in conclusion, no mass is being created by plants, they just temporarily capture energy into mass.”
So, is energy converted to mass after all by photosynthesis. If only temporarily?
If you have a closed glass aquarium, with a plant in it and all necessary ingredients, and sunlight shining on it. Will it’s mass increase by small amount if only temporarily?

The plant will increase in mass, but the total mass inside the aquarium should remain the same. This is because the energy in sunlight is used to combine CO2 and H20 into glucose. (via reducing NADP+ into NADPH, which in turn reduces CO2 to glucose in the Calvin cycle.)
So it might be best to think that the energy of the sunlight is stored in the potential energy between the atoms in glucose, and while the bonds hold potential energy, they don’t add mass to the system. (Being POTENTIAL energy)

If the energy from the sun is captured by the plants then the mass of the earth is increasing but the mass of the universe stays the same. The energy has just transferred from the Sun to planet earth. Correct?

If so, I would imagine that the plants build up the mass of the earth and by their dying and re-growing they add centimeters to the earth’s circumference. Correct?

In this case I think you are right. For some reason the author and others who write on this topic think that the chemical bonds between atoms represent a ‘miniscule’ amount of mass, which does not make sense and should have been intuitively rejected based upon the fact that these particular bonds were generated via photosynthesis thanks to photons, which are massless particles, so why and how (other than magically) could they be converted to mass in chemical bonds? As you stated, no matter, no mass.

The query posted by Erin on 24 March 2015 has not been answered. Archeologists and geologists relate the depth of burial of decayed organic matter to its age, ie oldest is deepest, except where erosion or land upheaval may have occurred locally (take coal,for example). So why are you ‘scientists’ denying that energy from the sun does not convert into deposits of plant matter, which also have mass?

I am glad to see that there are others, albeit very few, who realize that the earth is growing larger due to photosynthesis. It amazes me that it could be so obvious and yet so ignored but then again they used to think it was flat.